Firefox help needed

OK, my software stupidity has settled in again...

I'm running Firefox as a browser, XP Pro as an OS. I upgraded my Adobe Acrobat from 5 to 7 and suddenly, Firefox won't use it as a plug-in. Under the tools->options->downloads menu, the file types box on the bottom is empty and the "change action" and "remove" buttons are shaded out (inactive). The "plug ins" button still works and I can pull up the list- which does have Acrobat on it.

When opening existing or downloaded files from my hard disk, Acrobat works just fine. It's just that I can't seem to make it work as a Firefox plug-in.
According to the Mozilla website:

"On Windows, simply install Adobe Reader. Mozilla will detect the browser plugin if Adobe Reader is installed, and the Adobe Reader installer will install the plugin automatically if you install Adobe Reader after Mozilla.

"If you are upgrading from Adobe Reader 6.0.x to Adobe Reader 7.0, uninstall any updates first, in order of installation, then uninstall Adobe Reader. This will ensure a clean upgrade to 7.0. "

It sounds like this was the cause of the problem. Now, what to do about it? Try this:

"How can I remove the Acrobat Plugin?

"Delete the file named nppdf32.dll from your Mozilla Firefox plugins folder. You may have to enable showing hidden files to do this."

Good luck....